This project is designed to investigate the effects of PCB congeners of PCB congeners 2,4,2',4 tetrachlorobiphenyl and 3,4,3',4' tetrachlorobiphenyl (TCBs) on the maternal and sexual behaviors of laboratory rats. Preliminary observations indicate that treatment of pregnant rats with TCBs produce behavioral effects that interfere with the display of normal maternal behavior. The experiments included in the first part of the proposal test hypothesis about the endocrine and neurochemical causes of these behavioral effects of TCBs. Specifically, the work investigates how the hormones of pregnancy and lactation modulate the toxic effects of TCBs on the dopaminergic pathway from the substantial nigra to the basal ganglia. The second part of the proposal focuses on the effects of prenatal and neonatal exposure to TCBs on the development of female sexual behavior. The central hypothesis tested here is that TCBs prevent the development of normal sexual behavior by affecting the development of dopaminergic systems. These dopaminergic pathways are responsible for the motivational and motoric aspects of female sexual behavior. This work makes use of sensitive behavioral anatomical and neurochemical approaches and the anticipated results will greatly expand our understanding of the effects of environmental contaminants on brain function and behavior. This work also begins to differentiate between developmental effects of TCBs that are due to direct actions on the developing nervous system from those that are the indirect result of change sin the quality of maternal care.